Methanogens dynamics and ascaris inactivation in thermal septic tank | |
| Author | Nan Kham Syne |
| Call Number | AIT Thesis no.EV-13-13 |
| Subject(s) | Septic tanks Sewage--Purification--Anaerobic treatment |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Abstract | The sparking potential environmental sanitation problems linked to the lower effluent quality from current on site sanitation systems, non-hygienical way of sewage sludge disposing and reusing have fostered the need of newer technology to generate the better quality products. Recently, anaerobic sewage sludge digestion under thermophilic condition has gaining much higher attention for its higher biodegradation and pathogenic inactivation capability with generation of valuable by products such as biogas and fertilizer. In an attempt to better understand the process of sewage sludge digestion under different thermal treatment, this study mainly concentrated on microbiological level to elucidate microbial community population of septic tank operating in different temperatures by applying novel techniques, namely, Fluorescence In Situ Hybridization (FISH) and Polymerase Chain Reaction (PCR) were used. Seven probes were used in in situ analysis and eleven probes were used for PCR to identified methanogenic archaea population at each temperature. The FISH analysis revealed the order and family level methanogenic archaea present at different temperature followed by PCR method to specified the detail genera of methanogens and their population dynamics. Both techniques confirmed that Methanosarcina acetivorans is main dominant species at control (32±3 ̊C) temperature while higher amount of Methanolinea tarda and Methanothermobacter thermoautotrophs were observed at 40 ̊C temperature. Lesser Methanogenic archaea diversity and dynamics showed at two thermophilic temperatures along with the dominance of Methanolinea tarda at 50 ̊C and Methanothermobacter thermoautotrophs at 60 ̊C. Beside the presence of these methanogens species, maximum biogas production was occurred at 40 ̊C with the minimum production from the reactor operated at control temperature. Furthermore, it was detected that thermophilic condition performed the inactivation of pathogens well over mesophilic condition. The result shows the inactivation rate of Ascaris lumbricoides at 60 ̊C is much higher than the rate of control temperature. Greater than 2 log reduction was achieved at 60 ̊C within three hours, following by 50 ̊C within 12 hours. In contrast, 1 log reduction was found within 24 hours at 40 ̊C and no log reduction was occurred at control temperature even after 24 hours. After BMP test process, significant reduction of COD was observed 68.7%, 79.5%, 84.4% and 78.2% respectively in control, 40 ̊C, 50 ̊C and 60 ̊C at the end of 30 days. Importantly almost 33-49.1% and 35-50.6%of Volatile solid were reduced from two types of samples (S and SI). Highest methane level was observed at 40 ̊C but maximum biogas production was found at 50 ̊C. Meanwhile, highest methane level of septic tanks was occurred at control and 60 ̊C and 40 ̊C septic tank produced maximum biogas. |
| Year | 2013 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering (EV) |
| Chairperson(s) | Thammarat Koottatep; |
| Examination Committee(s) | Shipin, Oleg V.;Chongrak Polprasert; |
| Scholarship Donor(s) | Greater Mekong Subregion (GMS) Scholarship; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2013 |